1. Field of the Invention
This invention relates to fuels, such as alcohol-blended fuels and, more particularly, to a method of reversing phase separation caused by exposure of alcohol-blended fuels to water.
2. Background Art
Alcohols have been used as additives in motor fuel to boost octane, oxygenate, extend fuel supply, replace ethers, and reduce the impact of fossil fuels on the carbon cycle.
One major problem with alcohol-blended fuels is their tendency to phase separate, when they are exposed to water, into a denser, alcohol-water layer, leaving a less dense, fuel layer depleted of octane rating and alcohol soluble hydrocarbons.
With alcohol-free fuels, water that is present is heavier and drops to the bottom of a container/tank. As long as a proper maintenance program is followed, the water level in the container/tank will never achieve the level of an intake for a pump that draws the fuel from the container/tank. By reason of their makeup, alcohol-blended fuels react differently than alcohol-free fuels in the presence of water.
Most common of the alcohol-blended fuels are ethanol-blended fuels. Ethanol is hygroscopic, meaning that it seeks out, and retains, water. At low water level concentrations, the ethanol is able to retain the water it has dissolved and remain associated with the fuel, whereby the fuel, water, and alcohol mixture remains stable and usable as a motor fuel. Once the water concentration exceeds a certain temperature-dependent threshold for the alcohol concentration, fuel-hydrocarbon content, and additives in the fuel, which typically contain alcohol as a major component, the ethanol and water phase separates from the fuel mixture. Under average temperature conditions in the United States a water content of 0.3% to 0.5% by volume is typical of a range within which phase separation occurs.
Generally, the alcohol-water layer will not support combustion in a conventional gasoline engine, such as those in vehicles, and, if introduced thereinto, may cause vehicle engine malfunction. At the same time, the upper fuel layer is depleted in octane rating and is likely out of spec for use as a motor fuel.
Because of its detrimental effects, the industry has for decades taken steps to avoid phase separation. Typically, additives have been introduced to the fuel to increase the water tolerance of the alcohol-blended fuel with the objective of avoiding phase separation. However, this approach has not prevented all cases of phase separation.
Currently, when phase separation does occur in a container/tank, the contents of the container/tank is pumped out and delivered to an appropriate facility for reconstitution. The container/tank is then cleaned preparatory to introducing a new supply of fuel.
At a filling station, phase separation has very significant economic consequences. The owner/operator thereof not only loses revenue from unsold fuel, but incurs the expense to haul the removed fuel away to be either reconstituted or discarded. Additionally, expenses are incurred in cleaning the emptied container/tank. The owner/operator must then additionally refill the container/tank while incurring even further losses by reason of the fact that the container/tank was out of commission while the above steps were carried out.
As phase separation occurs, the fuel can become an emulsion that is cloudy or hazy before denser material actually settles to the bottom of a container/tank. In the past, this condition has been treated with de-emulsifying agents to allow the emulsion to go back into the fuel mixture. This has commonly been accomplished with a nonionic surfactant of an alkanoic acid derivative.